Sealed annealing apparatus



May 8, 1956 w. E. ENGELHARD 2,744,745

SEALED vANrmALING APPARATUS Filed May 27,v 1954 ////l//\///////L//l//,

WAM/AM l ENG e.: f/mqp BYg ATTORNEY United States Patent' O SEALEDANNEALING APPARATUS William E. Engelhard, North Arlington, N. J.

Application May 27, 1954, Serial No. 432,829

3 Claims. (Cl. 2665) This invention relates to retorts for work to beannealed in high temperature furnaces, for example in the brighthardening and annealing of stainless steels, magnetic alloys and otherobjects, for copper brazing, and for other work. It is applicable t-oany system wherein it is desirable to blanket the work in hydrogen orother gas which must be dry during the annealing or other operations.

It has been the practice heretofore to position the work in a housinghaving an open upper end, and then to weld a plate completely onto theupper end of the housing. Said plate would have a gas inlet pipe securedthereto for discharge into the housing; a plurality of dischargeapertures were provided at the lower end of the housing. In such priorconstructions, it was necessary to continuously pump substantialquantities of the gas. with which the work was to be surrounded, toprevent a return flow of moisture laden air which would contaminate thework. This procedure involved not only the initial complete weldingoperation above referred, and subsequent breaking of the weld (bothcostly and time consuming operations) but also required the continuouspumping and wastage of very substantial amounts of gas.

It has also been the practice, heretofore, to provide complicatedapparatus for the purpose, requiring large space for installation andoperation, and requiring very special handling of the work and in theexercise of the critical controls for operating conditions. In suchprior constructions, it was necessary to continuouslyfpump substantialquantities of the gas with which the work was to be surrounded, tocompensate for diiusion and contamination of the gas by moisture ladenair which would spoil the work, and the inner work containing housinghad to be made of expensive alloys.

Previous procedures required continuous pumping and wastage of verysubstantial amounts of gas during operation of the furnace, in an effortto prevent contamination.

In an elort to prevent contamination of the interior Workk containingchamber, it has been the practice to provide elongated, partitionedhorizontal sectional chambers in which the work was positioned; thesechambers were sectionally isolated and cleaned; through them substantialquantities of gas had to be pumped. This required the use and wastage ofconsiderable quantities of gas, involved elaborate and complexmechanisms, and was a costly, expensive and time-consuming operation.

The present invention obviates the objections to the practices in thisart above noted and others inherent in prior methods. improved resultsare attained by the method and apparatus of this invention, pursuant towhich the work may be placed in the furnace and removed therefrom andthe connection to the gas source made and discontinued, in a novel,ingenious, eicient and advanice tageous manner. Pursuant 'to thisinvention, the gas is maintained pure and dry and the dew-point keptlow, factors contributing importantly to the novel and successful methodof this invention. The method and apparatus of this invention enable theannealing operation to be performed in a Vrelatively pure atmosphere ofdry gas pumped through a path completely bathing the objects to beannealed, thence through a'path deiined by alpair of spaced walls, anddischarged. Pursuant to the method and apparatus of this invention aconsiderable saving is effected in the apparatus and method ofoperation, only minor quantities of gas are required for operation, thework is kept bathed in a relatively dry gas, the inner or workcontaining casing may be made of inexpensive iron or other material, andthe insertion of the work into the furnace and its removal therefrom maybe attained in a no vel and convenient manner.

These and other advantageous objects, which will appear from thedrawings and from the description hereinafter, are accomplished by thestructure of my invention of which an embodiment is illustrated in thedrawings. It will be apparent, from a consideration of said drawings,and the following description, that the invention may be embodied inother forms suggested thereby, and such other formsas come within thescope of the appended claims are to be considered within the `scope andpurview of the instant invention.

In the drawings, Fig. l is a vertical sectional-view, partly fragmentaryof a method and apparatus embodying the invention, and Fig. 2 is asimilar view of another form thereof.

As shown in Fig. l of the drawings, a retort constructed pursuant tothis invention comprises an inner casing 10 having a top wall 11 andside walls 12 depending therefrom and forming therewith an open lowerend 13 for the inner casing. An outercasing 17 is pr-ovided, comprisinga lower wall 18 and side walls 19 defining therewith an open upper end20 through which the inner casing may be inserted. The parts are soproportioned that the inner casing may be readily positioned interiorlyof the outer casing to be completely encompassed therein, with the walls12 and 19 of the said casing preferably spaced apart for passage of thegas pumped through the apparatus, with enough room to allow forreasonable warpage and distortion of the parts at high temperatures.Illustrative Figs. l and 2 necessarily are not to scale. The open lowerend 13 lof the inner casing is disposed in spaced relation'to the lowerWall 18 of the outer casing. Thus there is provided a continuous pathfor the tlow of gas from the inner casing, out of the open lower end 13thereof and intermediate the inner and outer walls of said casings inthe direction indicated by the arrows in Fig. l. An atmosphericcontamination seal to preclude entry of moisture-laden air is shown as acontinuous barrier ring 24 positioned intermediate the open end 13 ofthe inner casing 10 and the lower wall 18 of the outer casing, By thearrangement described, the hydrogen or other ,gas with which the work isto be blanketed during the annealing operation may be pumped through thegas pipe 264which is preferably xed to the top wall 11 of the innercasing (as at 27) blanketing said work and thence through the barrierring 24 and intermediate the walls 12 and 19 of the inner and outercasings, and to the atmosphere, The ring 24 may be made of siliconcarbide wool or other material which provides restricted openings forthe gas to filter through but which will not permit the reversediffusion of contamination-laden atmospheric air.

The gas is pumped through the pipe 26 under pressure so as tocontinually bathe the work in the inner casing therein. The velocity ofthe gas passing through the openings of barrier ring 24 in the directionindicated by the arrows will be so great as to effectively prevent theback-flow of air through said ring and into the interior of the innercasing. Back flow of air would carry moisture and would contaminate boththe gas in the inner casing 10 and the work being annealed. Thus thedewpoint is kept to an absolute minimum, pursuant to this invention.Also, by virtue of this protection afforded the inner casing 10, thelatter may be made of relatively inexpensive material, such as ordinaryiron, whereas heretofore it has been necessary to make the casing whichis to hold the work (the inner casing) of expensive alloys to resistcontamination by the atmosphere.

The disposition of ring 24 intermediate the casings and in the path offlow of the gas, plus the spacing of the walls 12, 19 of the inner andouter casings serve to accelerate the movement of gas in the directionof the arrows, affording a further safeguard against contamination ofthe inner casing by atmospheric air.

The invention may be used in connection with any high temperatureannealing furnace, such as that shown at 28 in Fig. 1 having heatingmeans such as elements 29 and the opening 30 to receive the parts abovementioned. Said opening may be closed by cover 31 or the like.

A plate 35 is provided, having angularly directed marginal edges 36adapted to be telescopically received within oppositely directed iiangemember 37 secured to or unitary with the upper end of side wall 19 ofouter casing 17. A sleeve 3S is fixed to the plate 35 as at 45 andsurrounds an opening therein, said sleeve being so proportioned as toencircle the pipe 26 and define therewith a passage 32 for the flow ofthe gas as indicated by the arrows in Fig. 1. Discharge pipe 23 isconnected to the sleeve 38 at one end and at the other end opens intothe atmosphere 25. A moisture and atmospheric air barrier ring 41 suchas silicon carbide sand, may be provided within the flange member 37 sothat when the marginal edge 36 of the plate 35 is seated therein, theplate 35 will effectively close the top of outer casing 17. In thearrangement described, the work may be positioned in inner casing 11 oron the lower end 18 of outer casing 17, and then the inner casing 11 isin-serted into the outer casing to the position shown in Fig. l. Plate35 (and sieeve 38) may then be positioned on the inner casing.

Finally the cover 31 may be secured in place. The cover 31 may be formedin sections having an opening 33 for sleeve 38, for convenience ofapplication. The plate 35, sleeve 38, and discharge pipe 23 essentiallyconstitute a housing disposed on the upper end of the outer casing 17,defining a path for the discharge of gases pumped through barrier 24, asindicated by the arrows. The pipe 26 described may be connected to a gassource 42 by means of a suitable coupling 43 or the like and the upperend of sleeve 38 may be sealed to pipe 26 by a separable or integralstufiing box 48, in which the pipe 26 may be vertically slidable. Thusit will be seen that the invention provides a very convenient means forinitially positioning the work in and removing it from the heatingfurnace, there is very little loss of the hydrogen or other gas, whichis being pumped into the inner casing within the furnace, and the systemoperates eiiiciently at a fraction of the quantity of gas previouslyrequired for the purposes.

The form of invention shown in Fig. 2 essentially corresponds with thatof Fig. l (like parts being correspondingly numbered for facility ofreference) except that the inner casing 10 in Fig. 2 is showntelcscopically disposed on a work receiving and holding open housing 44,shown disposed on the bottom wall 18 of the outer casing 17. The gaspipe 26 in the Fig. 2 construction is extended downwardly preferablythrough the top wall 11 of inner casing 10 and may be extended to apoint adjacent the lower wall 18 of work receiving housing 44 as byproviding a pipe 47 telescopically arranged therein, the upper end ofpipe i7 being connected to the gas source 42 through a suitable coupling43 and being slidably sealed to pipe 26 through stuffing box 46. Thepath of the gas is marked by arrows in Fig. 2; after reversing itscourse, from the lower end of pipe 47, the gas bathes the work andflowing out of the top of housing 44, passes downwardly intermediate thewall 12 of casing 10 and housing 44, thence upwardly between walls 12and 11i etc. (as in Fig. l). The sleeve 38 is sealed to gas pipe 26 bystuffing box 48. in the Fig. 2 form the parts 3S and 35 might beconnected together at 45 as one unit, essentially, and pipe 26 andcasing l@ another unit, at 27 if desired. Other variations of thespecific form of method and apparatus will become apparent from aconsideration of the disclosure herein; all such other forms, comingwithin scope of the appended claims, shall be deemed to be coveredthereby.

In performing the method of the invention shown in Fig. l, starting withsimply the furnace 2S open at 30 and the outer casing 17 positionedtherein, the work is Y placed on the lower end 13 of the outer casing17, or positioned interiorly of the inner casing 10, then said innercasing (with gas pipe 26 aiiixed thereto as at 27) is positioned in theouter casing, with the lower end 13 of the inner casing disposed on thebarrier ring 24. Sleeve 38 and aixed plate 35 are positioned over pipe26 and flange 36 of the plate 35 is positioned in the sand seal 41. Thenthe cover 31 is positioned atop the furnace opening 30, closing aroundthe opening 33 for sleeve 3S. Connection of pipe 26 with a gas source 42may be made by a suitable coupling 43 so that the source 42 may beswingably disposed relative thereto; in this fashion rapid connectionand disconnection of the parts may be attained.

ln the Fig. 2 form a similar procedure is followed, except that the pipe47 is provided to carry the gas down to a point adjacent the bottom ofthe work receiving housing 44.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

1. A device for annealing work in a gas atmosphere, in the opening of ahigh temperature furnace, said opening having a bottom and side walls,said device comprising an outer casing adapted to be positioned on thebottom wall of the casing opening and having side walls extendingupwardly from the bottom wall of the casing opening in spaced relationto the side walls of said opening, said side walls of the casingdefining, at their upper ends an opening, an inner casing adapted to bepositioned within the outer casing through `said opening, said innercasing having a top wall and side walls depending therefrom, a gas inletpipe iixed to the top wall of the inner casing and projecting into theinterior of the inner casing, a cover plate for the outer casing,complementary means on the upper ends of the side wall of the outercasing and on the perimeter of said cover plate for sealing said upperend and perimeter said cover plate having a medial opening, a sleevefixed to the cover plate in registry with the opening therein and a gasdischarge pipe secured to the sleeve at a point substantially above thepoint of connection of the sleeve with the cover plate, said pipedischarging into the atmosphere, and means for connection of the gasinlet pipe to a source of supply of gas, whereby gas may be pumpedthrough said pipe and thus through the inner casing, between the innerand outer casing walls and thence between the sleeve and gas inlet pipeand out of the gas discharge pipe to the atmosphere.

2. In a device for annealing work as set forth in claim l, a barrierring intermediate the lower end of the inner casing and the side wall ofthe outer casing, through which the gas must pass.

claim 1; between inner and outer walls, sleeve and gas 10 inlet pipe andout of the gas discharge pipe.

1. A DEVICE FOR ANNEALING WORK IN A GAS ATMOSPHERE, IN THE OPENING OF AHIGH TEMPERATURE FURNACE, SAID OPENING HAVING A BOTTOM AND SIDE WALLS,SAID DEVICE COMPRISING AN OUTER CASING ADAPTED TO BE POSITIONED ON THEBOTTOM WALL OF THE CASING OPENING AND HAVING SIDE WALLS EXTENDINGUPWARDLY FROM THE BOTTOM WALL OF THE CASING OPENING IN SPACED RELATIONTO THE SIDE WALLS OF SAID OPENING, SAID SIDE WALLS OF THE CASINGDEFINING, AT THEIR UPPER ENDS AN OPENING, AN INNER CASING ADAPTED TO BEPOSITIONED WITHIN THE OUTER CASING THROUGH SAID OPENING, SAID INNERCASING HAVING A TOP WALL AND SIDE WALLS DEPENDING THEREFROM, A GAS INLETPIPE FIXED TO THE TOP WALL OF THE INNER CASING AND PROJECTING INTO THEINTERIOR OF THE INNER CASING, A COVER PLATE FOR THE OUTER CASING,COMPLEMENTARY MEANS ON THE UPPER ENDS OF THE SIDE WALL OF THE OUTERCASING AND ON THE PERIMETER OF SAID COVER PLATE FOR SEALING SAID UPPEREND AND PERIMETER SAID COVER PLATE HAVING A MEDIAL OPENING, A SLEEVEFIXED TO THE COVER PLATE IN REGISTRY WITH THE OPENING THEREIN AND A GASDISCHARGE PIPE SECURED TO THE SLEEVE AT A POINT SUBSTANTIALLY ABOVE THEPOINT OF CONNECTION OF THE SLEEVE WITH THE COVER PLATE, SAID PIPEDISCHARGING INTO THE ATMOSPHERE, AND MEANS FOR CONNECTION OF THE GASINLET PIPE TO A SOURCE OF SUPPLY OF GAS, WHEREBY GAS MAY BE PUMPEDTHROUGH SAID PIPE AND THUS THROUGH THE INNER CASING, BETWEEN THE INNERAND OUTER CASING WALLS AND THENCE BETWEEN THE SLEEVE AND GAS INLET PIPEAND OUT OF THE GAS DISCHARGE PIPE TO THE ATMOSPHERE.